1. Field of the Invention
This invention is generally directed to locking devices for entry doors such as doors opening into a residence or an apartment and more specifically to security bar locks of the type having an elongated rod having one end attached to a keeper that is mounted to the rear of the door in spaced relationship with respect to the floor and wherein the other end of the rod or extension member acts as a brace when the lower end is abutted against the floor or an abutment member mounted to the floor.
2. History of the Related Art
There have been many attempts to provide security locks for use on entry doors so as to prohibit the unauthorized opening of the doors. As demands grow for increased security many individuals have begun supplementing the common doorknob type of entry lock with other types of locks including dead bolt mechanisms which are mounted to the door frame and which cooperate with sliding locks carried by the door. Some problems with the use of supplemental locks having components which are mounted to a door frame are that additional sets of keys are necessary for each of the separate locking mechanisms and such locking mechanisms may be bypassed by tampering with the door frame and therefore the amount of security provided is directly dependent upon the strength of the door frame.
Another problem with locking mechanisms between a door and a door frame is that generally the locks operate only to retain the door in a closed position relative to the door frame. In some instances, it may be necessary for an individual to open a door a limited amount to determine the identity of the individual seeking entry. To provide limited security in these events conventional use is normally made of a chain attachment which extends from a keeper mounted o the door frame to a secondary keeper mounted on the back of the door. Unfortunately, chain-like restraint devices are easily bypassed, either by manipulation of the chain relative to the keepers, by placing force on the door to withdraw the keepers from the door frame or by tampering with the chain directly such as by cutting the chain in order to gain entry. In view of the foregoing problems and the continuing desire to provide for increased security many attempts have been made to provide for special bracing mechanisms which are mounted to the rear of the door and which are braced against the floor. Such bracing mechanisms offer a benefit over conventional door frame mounted locks in that the braces cannot be easily accessed by an individual trying to obtain unlawful or unauthorized entry. Further, the braces are not dependent upon the strength of the door frame but rather transfer force directly to the floor and its underlying supports which are designed to withstand a great deal more force that are conventional door frames.
Conventional brace-type door jams or locks generally include a keeper element which is attached to the door generally in spaced relationship with respect to the floor and in which keeper element is pivotally mounted one end of a brace rod or extension member. The opposite end of the brace rod or extension member includes a foot portion which may include a of friction plate that is engaged with the floor or may include a portion which is engageable with an abutment member attached to the floor. In this manner, when the brace rod is lowered into a position wherein the door is locked relative to the door frame any attempt to open the door will cause force to be transmitted along the length of the rod whereby the floor will absorb the energy of the force being applied. The greater the amount of force applied to the door the tighter the brace becomes. When it is desired to open the door it is only necessary to raise the brace rod relative to the floor. In many conventional brace-like door locks retainers are provided for retaining the brace rods in an elevated position when not in use.
Unfortunately, there are drawbacks associated with most conventional brace-type security door locks. As with many dead bolt-type door locks, which are attached to a door frame, most brace-type security door locks do not permit any opening of the door when the braces associated with such locking mechanisms are in place. Therefore, it is not possible for a person to secure a door in a partially opened position when opening the door to determine if a person seeking entry is an authorized individual. Another drawback with conventional brace-type door locks is that the locks can be manipulated by children after adults have left the premises. Under such circumstances it is possible for a child to lock themselves within an area while preventing the adult from regaining entry. This situation cannot only be emotionally disturbing for a child who is locked within an area, but could be potentially hazardous for a child in the event some occurrence were to take place in which entry into the area was absolutely necessary, such as in the case of fire.
Other problems inherent with conventional brace-type door locks are that the mechanisms tend to be mechanically difficult and therefore expensive to purchase and install. Many brace-type door locks include complicated ratchet adjustments or telescoping members which all must be adjusted for a given installation. The more complicated the locking mechanism is to use or to install the less likely it is that the locking mechanism will be utilized by the individual for which the mechanism has been provided.
In view of the foregoing, it is necessary to provide a brace-type locking mechanism which provides the benefit of increased strength which also allows for a limited opening of a door to determine the identity of an individual seeking entry or to allow for limited ventilation, as well as to provide a locking mechanism which is cost efficient and easy to install and one which can be easily dismantled so that the lock may not be utilized by children when an adult is not present within a given area.
Some examples of prior art door brace restraints or locks are disclosed in U.S. Pat. Nos. 1,810,186 to Richards; 1,879,119 to Dauble; 1,944,783 to Ciriacy et al.; 1,966,612 to Cochran; 4,456,291 to Brogie; and 4,822,086 to Brown.